Pentax lenses; determining if Av capable vs M mode

**Oakland Rob** · 08-06-2021, 11:07 AM

From just looking at the lenses how does one determine if it requires setting the camera in M mode, vs being able to use Av (or P)?

My SMC Pentax M 35mm f2.8 lens and SMC Pentax 28mm f3.5 only work in M. But my smc Pentax M 200mm F4 works in P/Av.

I can keep it straight by marking those, but now I'm curious about why some only work in M but not Av. None have the auto-aperture setting.

**othar** · 08-06-2021, 11:20 AM - **1 Like**

Originally posted by Oakland Rob

But my smc Pentax M 200mm F4 works in P/Av.

I think you should check that again, when set to P or Av with a lens without the A-setting on the aperture ring (or when the aperture ring is set to somewhere else) the camera will still take pictures in a semi Av mode (with all the lenses you mentioned), but it will only use the lenses wide open

**Oakland Rob** · 08-06-2021, 11:35 AM - **1 Like**

Doh! You're right. I must have left it in M. You can hear it stop down when the green button is pushed, so the absence of that should have alerted me that it was working the same as the others.

So sorry...my bad. Never mind,

Adam · 08-06-2021, 11:44 AM

Originally posted by Oakland Rob

From just looking at the lenses how does one determine if it requires setting the camera in M mode, vs being able to use Av (or P)?

My SMC Pentax M 35mm f2.8 lens and SMC Pentax 28mm f3.5 only work in M. But my smc Pentax M 200mm F4 works in P/Av.

I can keep it straight by marking those, but now I'm curious about why some only work in M but not Av. None have the auto-aperture setting.

Here are some resources, though as already noted, things will generally be consistent across an entire lens series:
The Pentax K-mount Camera Lens Compatibility Chart

Check Lens Compatibility with Your Pentax Camera

Adam
PentaxForums.com Webmaster (Site Usage Guide | Site Help | My Photography)

PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

08-06-2021, 11:07 AM	#1
Oakland Rob Loyal Site Supporter Join Date: Apr 2015 Location: Bay Area California Photos: Gallery \| Albums Posts: 798	Pentax lenses; determining if Av capable vs M mode From just looking at the lenses how does one determine if it requires setting the camera in M mode, vs being able to use Av (or P)? My SMC Pentax M 35mm f2.8 lens and SMC Pentax 28mm f3.5 only work in M. But my smc Pentax M 200mm F4 works in P/Av. I can keep it straight by marking those, but now I'm curious about why some only work in M but not Av. None have the auto-aperture setting.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Pentax K-3, Manual Mode won't switch to Av, Bulb, but stays in M Mode	scotman55	Troubleshooting and Beginner Help	5	10-10-2022 07:17 AM
Difference between Av mode and M mode on fixed aperture lens.	micl161	Pentax SLR Lens Discussion	12	10-04-2018 08:50 PM
K-5 vs MZ-S vs LX vs PZ-1p vs ist*D vs K10D vs K20D vs K-7 vs.......	Steelski	Pentax K-5 & K-5 II	2	06-28-2017 04:59 PM
Pentax K1, wireless mode for Pentax Flash unit AF-540FGZ is capable and functional	George H Pearson	Pentax K-1 & K-1 II	3	05-27-2017 12:16 AM
New camera mode idea: Av-R (Av Relative)	Jonathan Mac	Photographic Technique	6	04-15-2012 09:45 PM

08-06-2021, 11:20 AM - 1 Like	#2
othar Site Supporter Join Date: May 2014 Location: Linz Photos: Albums Posts: 3,098	Originally posted by Oakland Rob But my smc Pentax M 200mm F4 works in P/Av. I think you should check that again, when set to P or Av with a lens without the A-setting on the aperture ring (or when the aperture ring is set to somewhere else) the camera will still take pictures in a semi Av mode (with all the lenses you mentioned), but it will only use the lenses wide open

08-06-2021, 11:35 AM - 1 Like	#3
Oakland Rob Loyal Site Supporter Join Date: Apr 2015 Location: Bay Area California Photos: Gallery \| Albums Posts: 798 Original Poster	Doh! You're right. I must have left it in M. You can hear it stop down when the green button is pushed, so the absence of that should have alerted me that it was working the same as the others. So sorry...my bad. Never mind,

08-06-2021, 11:44 AM	#4
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	Originally posted by Oakland Rob From just looking at the lenses how does one determine if it requires setting the camera in M mode, vs being able to use Av (or P)? My SMC Pentax M 35mm f2.8 lens and SMC Pentax 28mm f3.5 only work in M. But my smc Pentax M 200mm F4 works in P/Av. I can keep it straight by marking those, but now I'm curious about why some only work in M but not Av. None have the auto-aperture setting. Here are some resources, though as already noted, things will generally be consistent across an entire lens series: The Pentax K-mount Camera Lens Compatibility Chart Check Lens Compatibility with Your Pentax Camera Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers: